From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 3366AEB64DD for ; Thu, 13 Jul 2023 08:10:15 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234019AbjGMIKN (ORCPT ); Thu, 13 Jul 2023 04:10:13 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:50280 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233746AbjGMIJm (ORCPT ); Thu, 13 Jul 2023 04:09:42 -0400 Received: from desiato.infradead.org (desiato.infradead.org [IPv6:2001:8b0:10b:1:d65d:64ff:fe57:4e05]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 29266270F; Thu, 13 Jul 2023 01:08:09 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=desiato.20200630; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=u0MMSF1BzosWHENbYjUkiziMMb6fnm98Zn1xzxHch2A=; b=GcPFOkaVfv+4rWtqRq8f5/Hg0C x759LYiWrisgCwDLlpY2O5kMsCKvp1CACLcajs6VC/SI7OkTmvqwKDH0vrQBiepAlY9dbKWyTGlq8 DQ/mhqwAc/Gl9wFClxqPmww6pSrSVBG6ZxSn/f6lNnxdWTRaqr+sPiZc1EQ7tugcBDGY9kyPHGydj /Wk5qSXzPmrzLHH6tEYIXOMLDH7yPcp3rr1xelU5HdF+sgT6pT9iL94XLl9SZ76mCLXvhehQ6g/RD G3bjvsCIt/qZxgCUmGJuBeqOXvgC4nyfH7WnOt0yN8ntFD3SwIoDJqaRBzlsPjGsDoRdlNKwfbNHF 7WbIj6pw==; Received: from j130084.upc-j.chello.nl ([24.132.130.84] helo=noisy.programming.kicks-ass.net) by desiato.infradead.org with esmtpsa (Exim 4.96 #2 (Red Hat Linux)) id 1qJrMY-004YHC-0d; Thu, 13 Jul 2023 08:07:46 +0000 Received: from hirez.programming.kicks-ass.net (hirez.programming.kicks-ass.net [192.168.1.225]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits)) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id 5AF54300222; Thu, 13 Jul 2023 10:07:45 +0200 (CEST) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 4476E266877EB; Thu, 13 Jul 2023 10:07:45 +0200 (CEST) Date: Thu, 13 Jul 2023 10:07:45 +0200 From: Peter Zijlstra To: Kai Huang Cc: kirill.shutemov@linux.intel.com, linux-kernel@vger.kernel.org, dave.hansen@intel.com, tglx@linutronix.de, bp@alien8.de, mingo@redhat.com, hpa@zytor.com, x86@kernel.org, seanjc@google.com, pbonzini@redhat.com, kvm@vger.kernel.org, isaku.yamahata@intel.com, sathyanarayanan.kuppuswamy@linux.intel.com Subject: Re: [PATCH 10/10] x86/virt/tdx: Allow SEAMCALL to handle #UD and #GP Message-ID: <20230713080745.GB3139243@hirez.programming.kicks-ass.net> References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Jul 12, 2023 at 08:55:24PM +1200, Kai Huang wrote: > @@ -85,6 +86,7 @@ > .endif /* \saved */ > > .if \host > +1: > seamcall > /* > * SEAMCALL instruction is essentially a VMExit from VMX root > @@ -99,6 +101,7 @@ > */ > mov $TDX_SEAMCALL_VMFAILINVALID, %rdi > cmovc %rdi, %rax > +2: > .else > tdcall > .endif This is just wrong, if the thing traps you should not do the return registers. And at this point the mov/cmovc thing doesn't make much sense either. > @@ -185,4 +188,21 @@ > > FRAME_END > RET > + > + .if \host > +3: > + /* > + * SEAMCALL caused #GP or #UD. By reaching here %eax contains > + * the trap number. Convert the trap number to the TDX error > + * code by setting TDX_SW_ERROR to the high 32-bits of %rax. > + * > + * Note cannot OR TDX_SW_ERROR directly to %rax as OR instruction > + * only accepts 32-bit immediate at most. > + */ > + movq $TDX_SW_ERROR, %r12 > + orq %r12, %rax > + jmp 2b > + > + _ASM_EXTABLE_FAULT(1b, 3b) > + .endif /* \host */ > .endm Also, please used named labels where possible and *please* keep asm directives unindented. --- a/arch/x86/virt/vmx/tdx/tdxcall.S +++ b/arch/x86/virt/vmx/tdx/tdxcall.S @@ -56,7 +56,7 @@ movq TDX_MODULE_r10(%rsi), %r10 movq TDX_MODULE_r11(%rsi), %r11 - .if \saved +.if \saved /* * Move additional input regs from the structure. For simplicity * assume that anything needs the callee-saved regs also tramples @@ -75,18 +75,18 @@ movq TDX_MODULE_r15(%rsi), %r15 movq TDX_MODULE_rbx(%rsi), %rbx - .if \ret +.if \ret /* Save the structure pointer as %rsi is about to be clobbered */ pushq %rsi - .endif +.endif movq TDX_MODULE_rdi(%rsi), %rdi /* %rsi needs to be done at last */ movq TDX_MODULE_rsi(%rsi), %rsi - .endif /* \saved */ +.endif /* \saved */ - .if \host -1: +.if \host +.Lseamcall: seamcall /* * SEAMCALL instruction is essentially a VMExit from VMX root @@ -99,15 +99,13 @@ * This value will never be used as actual SEAMCALL error code as * it is from the Reserved status code class. */ - mov $TDX_SEAMCALL_VMFAILINVALID, %rdi - cmovc %rdi, %rax -2: - .else + jc .Lseamfail +.else tdcall - .endif +.endif - .if \ret - .if \saved +.if \ret +.if \saved /* * Restore the structure from stack to saved the output registers * @@ -136,7 +134,7 @@ movq %r15, TDX_MODULE_r15(%rsi) movq %rbx, TDX_MODULE_rbx(%rsi) movq %rdi, TDX_MODULE_rdi(%rsi) - .endif /* \saved */ +.endif /* \saved */ /* Copy output regs to the structure */ movq %rcx, TDX_MODULE_rcx(%rsi) @@ -145,10 +143,11 @@ movq %r9, TDX_MODULE_r9(%rsi) movq %r10, TDX_MODULE_r10(%rsi) movq %r11, TDX_MODULE_r11(%rsi) - .endif /* \ret */ +.endif /* \ret */ - .if \saved - .if \ret +.Lout: +.if \saved +.if \ret /* * Clear registers shared by guest for VP.ENTER and VP.VMCALL to * prevent speculative use of values from guest/VMM, including @@ -170,13 +169,8 @@ xorq %r9, %r9 xorq %r10, %r10 xorq %r11, %r11 - xorq %r12, %r12 - xorq %r13, %r13 - xorq %r14, %r14 - xorq %r15, %r15 - xorq %rbx, %rbx xorq %rdi, %rdi - .endif /* \ret */ +.endif /* \ret */ /* Restore callee-saved GPRs as mandated by the x86_64 ABI */ popq %r15 @@ -184,13 +178,17 @@ popq %r13 popq %r12 popq %rbx - .endif /* \saved */ +.endif /* \saved */ FRAME_END RET - .if \host -3: +.if \host +.Lseamfail: + mov $TDX_SEAMCALL_VMFAILINVALID, %rax + jmp .Lout + +.Lseamtrap: /* * SEAMCALL caused #GP or #UD. By reaching here %eax contains * the trap number. Convert the trap number to the TDX error @@ -201,8 +199,8 @@ */ movq $TDX_SW_ERROR, %r12 orq %r12, %rax - jmp 2b + jmp .Lout - _ASM_EXTABLE_FAULT(1b, 3b) - .endif /* \host */ + _ASM_EXTABLE_FAULT(.Lseamcall, .Lseamtrap) +.endif /* \host */ .endm